Position responsive electrographic apparatus which use electrostatic technology, such as pen based computers and digitizers, require the generation of a large AC signal from a stylus transmitter device for detection by a receiver/controller. These position responsive electrographic apparatus are commonly known in the art, as exemplified by U.S. Pat. No. 5,225,637 entitled "Position Resolving System", U.S. Pat. No. 5,247,137 entitled "Autonomous Computer Input Device and Marking Instrument", and U.S. Pat. No. 4,672,154 entitled "Low Power, High Resolution Digitizing System with Cordless Pen/Mouse", all three of which are hereby incorporated by reference.
In portable applications, where weight, size and cost are of crucial importance, the stylus device generally needs to run off of low-cost, low-capacity, low-voltage and commercially available batteries. Since the coupling between the stylus transmitter and the receiver/controller circuit is weak, the AC signal required from the stylus is much larger than the supply voltage provided by the batteries. Therefore, an electronic means of amplifying the signal beyond that of the supply voltage is required.
Prior techniques for generating such amplified signals have used discrete circuitry containing numerous discrete components. These discrete component circuits suffer from high power dissipation and large component sizes, and thus limit the ability to reduce the size and weight of, and power dissipation within, the stylus.